This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. AgsA(aggregation-suppressing protein) is a novel small heat shock protein (sHsp) discovered in the thermally aggregated fraction from a Salmonella enterica serovar Typhimurium dnaK-null strain. It is strongly induced by high temperatures. The similarity between AgsA and the other two sHsps of Salmonella serovar Typhimurium, IbpA and IbpB, is rather low (around 30% amino acid sequence identity). Phylogenetic analysis suggested that AgsA arose from an ancient gene duplication or amplification at an early evolutionary stage of gram-negative bacteria. Biochemistry data suggest that AgsA is an effective chaperone capable of preventing aggregation of nonnative proteins and maintaining them in a state competent for refolding in Salmonella serovar Typhimurium at high temperatures. Sample of AgsA was multiplied in colibacillus by Xiaodong Shi, one coworker worked in ZengYi Chang's lab of Peking University. Preliminary data (mostly negative stain results) suggest that the particle of AgsA has a olive-like feature with a symmetry of D3. Comparing with its preventing aggregation stage(treat with insuline in room temperature), we can find remarkable distortion in the middle of it. One problem was found in the early research, AgsA seems likely to aggregate itself.This may effect the step of boxing the particles. Another problem is that AgsA are able to construct a fiber-like structure. Due to the similarity in width, it is really difficult to distinguish between particles and the small parts of the fiber. In the following experiment, we'd like to get a sub-nanometer model of two stages, one is the original stage and another is the preventing aggregation stage. We wish to find out what is the different between them. This may lead to finding a clue to how AgsA combines and prevents protein aggregation.